Method for aerating and drying granular materials



J. MAHO April 14, 1953 METHOD FOR AERATING AND DRYING GRANULAR MATERIALS Filed Jan. 14 1950 v INVENToR. Jacques Moho BY Rlkrli'hl i hav/'clou al@ WIWI@ m49. Ifo, All All. l

volume, the external air 4Water content of the air is to be possible to ventilate Patented Apr. 14, 1953 UNITED STATES PATENT I orrlcr;

METHOD FOR AERATING AND DRYING GRANULAR MATERIALS 4 Claims.

the present invention, the subjected to air currents taken from the outside air, these air currents being applied to successive layers of the stored material.

^ According to the present invention such inerchandise may be aerated throughout its entire having been previously conditioned by indirect contact with the heat generating merchandise. This indirect contact with the stored material tends to equalize the 4temperature of the incoming Ventilating air and that of the merchandise and causes the elimination or at least a considerable reduction of the water vapor content of the incoming outside air, and permits the direct use of the air thus preconditioncd for the aeration of the merchandise. Y

The method of the present invention permits the preservation in perfect conditioner stored merchandise solely by means of treatment withl the pre-conditioned air without it being necessary to transfer this merchandise from cell to cell as would be necessaryv in non-aerated ygranaries or warehouses which are only suitable for storage for a short time, whereas in the case of aerated `Warehouses the merchandise may be preserved for a long time at a materially reduced cost.

Heretofore, a serious problem has been encountered in the construction and operation of Vventilated warehouses or granaries, such as cereal silos for example, in that from the end of winter to the beginning of summer the rising temperature oi the outside air precedes that of the cereals which have been cooled during winter. In thisperiod there are iew occasions when the sufficiently low for it the cereals with this air without risking their humidification by condensaticn of the water oi the incoming air as it' `comes in contact with the cooler stored cereals. This condensation must beravoided in all cases.

.It should, moreover, be remarked that the various vparts of the volume of cereals may present differences either in temperature or humidity. In effect, in the lsilo cell the cereals are more corn-V pacted at the bottom than at the top by reason Aof thevgravitational pressure to `which they are subjected and in consequence it is in this base zone that the greatest resistance to aeration is encountered. Moreover, the biological or spontaneous heat inherently generated by the respiration of these cereals increases in the warehouse progressively towards the top and the air, thus heated, in rising carries with it the humidity which it has acquired towards the upper zones as a result the Water content of the cereals in the upper portions of the storage cell increases as well as their temperature. Account should also be taken of the effects of the temperature at the surface of the cereals, which effects are of great importance particularly in warehouses with horizontal floors. It also frequently occurs that cereals from Various sources are stored together in the same cell and that among them there is occasionally some damaged merchandise. All of these factors may be encountered in the same storage cell at widely different points both with respect to height and lateral position and which may cause the formation of dangerous concentration effects which can be limited and overcome by rapid and intensive aeration produced locally.

According to the present invention the required dehumidication of the incoming air is obtained by passing the incoming air over the external lwalls of the storage cell, which are inherently lincoming air, when it is at allower temperature than the walls of the storage cell, will absorb heat from the walls with a resulting decrease in its relative humidity. This decrease in humidity, pre-conditions the air. so that it is suitable for "direct application to the stored goods without danger of condensation of moisture and humidiiication of the stored materials.

Other and further objects will become apparent upon reading the following specification together with the accompanying drawing forming a part hereof.

Referring to the drawing:

Fig. 1 is a sectional View in elevation of a silo embodying the invention.

Fig. 2 is a vplan sectional View taken along the line 2-2 of Fig. 1.

Referring to Figs. 1 and 2 there will be seen one cell of a circular silo with two aeration flues 7 placed opposite one another and a closure member or pistons suspended by cable u may slide up or down in each of the aeration flues when the ,winch.t. is operated.. At .thelupper end of the two aeration ilues there is provided a by-pass passage lc through which the air may leave upwardly when the closure element s is located in the aeration iiue at its highest point as shown on the left side of drawing. In the opposite nue (that on the right of Fig. l) on the contrary, this element s closes the aeration flue at the level of the upper limit of the volume of stored cereal. The air under pressure is supplied by a fan (not shown) in this right hand flue and circulates as indicated by arrows transversely through the cereals or grains towards the left hand ue as well as the ues m and thence it escapes freely towards the top. It will be seen that simultaneous aeration is provided for all of the stored cereal or grains this aeration being eected throughout the entire height. Partia1 aeration may alsol be eected in Various height zones by lowering the closure element s down to the level II for example, in the left hand flue 7`.

In this case aeration is produced in the height zone having its upper limit determined on the Yright at level III and its lower limit on the left at level II. In this case the left hand ue is closed at its lowest part that is to say at the point where it connects with the horizontal air distribution network w which is connected to the fan. By lowering the closure element on the ,right to the' level II and the closure element on the left to level I, for example, the ventilation is effected in a zone which is limited at the top by level II and at the bottom by level I. It is Athus possible to eiect ventilation for each partial height zone which may be determined as required and if necessary it is possible to effect simultan neous ventilation of all of the cereals.

The drawing shows front and rear flues m, these iiues being without closure elements, and serving only for removing the air Coming from the cereal or grains which is exhausted through these ilues. Fig. 2 shows a plan sectional view according to which, it is possible to gain an idea of the arrangement of the four air flues 7' and m. It will be seen that the lues y' are so arranged that they have the double function of the infeed of the air Yto the cereal and the evacuation of the same air leaving the cereal, the flues m always serving for the evacuation of the air from the cereals. This figure also shows .by the direction of the arrows, the path traversed by the air.

In the base cone of the cell is arranged a bridge piece g which is shown in transverse section in Fig. 1. This bridge piece is located above the discharge opening of the cell. The cereals or grains now around this bridge piece down to the orifice when the cell is to be emptied. This bridge piece has the function of returning a part of the Ventilating air for the benefit of the cereals located in the base cone of the cell so that this part is also aerated. Moreover, :this bridge piece has for its object to prevent the grains from flowing principally from against the walls rather than from the centre during the emptying of the cell. The grains are thus mixed automatically on leaving the cell.

There will be seen 'in the upper part of the cell a lling tube e and a grain distributing cone r which has for its object to ensure an even lling and at the same time to prevent the cereals from accumulating on one side of thev cell only.

The winch t is intended for the operation of the closure elements and is located above the ceiling of the cell e, being formed in two parts so that the two halves of the drum on which the cord is wound may be easily separated one from the other, rotated with respect to each other and again re-coupled. It is thus possible to adjust rapidly the relative p-osition of the pistons either because of the lling height chosen or as a function of the height of the layer` which it is desired partially to ventilate. In this way there is only a single winch for operation of the cell.

In Fig. 1, the bottom conical wall of the silo cell is designated J, a is the main wall of the silo, d the cell separating walls, It the intermediate space or passage between the cells of the silo and a main wall, and z' the intermediate spaces or passages between the various silo cells, where a plurality of cells are used. These passages h and i are, moreover, like all the aeration pipes of the fvcharacter y' and connected at their lower ends Vthrough the passages h and z' will ybe heated by its contact with external walls of the cell, these walls being in direct contact with the stored grain. This reduces the humidity of the air before it is vused for aeration of the stored materials, without the necessity for specially treatingfthe air with heaters or the like, full advantage being taken of the spontaneous heat inherently generated by the stored grain. v

Where several cells are used, the incoming air may be drawn downwardly in all of the flues j and m, as through the passages h and i in one or more of the cells in order to obtain a greater degree of heat transfer from the stored grain. This air may be used for aerating another cell, the valves y being appropriately operated to provide the desired connections to the fan through the network w.

What I claim is:

l. The method of Ventilating granular matter stored in a container having lthermally conductive walls of relatively large area and a plurality of opposed perforated Ventilating ducts of relatively small cross-sectional area passing through said stored matter, which matter inherently generates spontaneous heat during such storage, comprising the steps of passing a conned stream of air at a temperature lower than that of the stored matter over said thermally conductive walls for equalizing the temperature between said air and said stored matter caused by said inherently generated heat, and thereafter causing said air to enter at least one of said ducts and emerge through its perforations into contact with said stored matter and traverse the same, and causing said air after contact with said stored matter to enter the perforations of a duct opposed to said rst-named duct, Aand then venting said air.

2. The method according to claim 1 wherein said thermally conductive walls are the vertical walls of said container and said air is rst passed downwardly over said walls and thence upwardly through at least one of said ducts.

3. The method according to claim l comprising the further step Iof producing a pressure differential and using said differential for causing said passage and said venting of said air.

4. The method according to claim 1 comprising the further steps of taking a portion of `said air after passage over said thermally conductive Walls, and directly venting said portion of said air for increasing the rate of heat transfer between said air and said stored matter without increasing the rate of ventilation of said stored matter.

JACQUES MAI-IO.

References Cited in the 131e of this patent UNITED STATES PATENTS Number Name Date 839,689 Williams Dec. 25, 1906 1,322,428 Gloess Nov. 18, 1919 Number Number Name Date Moore Dec. 4, 1928 Moore Dec. 4, 1928 Strub Oct. 3, 1933 McDowell et al. Oct. 8, 1935 Davis Jan. '7, 1936 Persons July 2, 1940 Bills Oct. 20, 1942 Solberg Mar. 6, 1945 FOREIGN PATENTS Country Date Sweden Sept. 10, 1940 

